/****************************************************************************
 * net/bluetooth/iob/iob_copyin.c
 *
 *   Copyright (C) 2014, 2016-2018 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <tinyara/config.h>

#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include <debug.h>

#include <tinyara/bluetooth/iob/iob.h>

#include "iob.h"

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

#ifndef MIN
#define MIN(a, b) ((a) < (b) ? (a) : (b))
#endif

/****************************************************************************
 * Private Types
 ****************************************************************************/

typedef CODE struct iob_s *(*iob_alloc_t)(bool throttled);

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: iob_copyin_internal
 *
 * Description:
 *  Copy data 'len' bytes from a user buffer into the I/O buffer chain,
 *  starting at 'offset', extending the chain as necessary.
 *
 * Returned Value:
 *  The number of uncopied bytes left if >= 0 OR a negative error code.
 *
 ****************************************************************************/

static int iob_copyin_internal(FAR struct iob_s *iob, FAR const uint8_t *src, unsigned int len, unsigned int offset, bool throttled, bool can_block)
{
	FAR struct iob_s *head = iob;
	FAR struct iob_s *next;
	FAR uint8_t *dest;
	unsigned int ncopy;
	unsigned int avail;
	unsigned int total = len;

	iobinfo("iob=%p len=%u offset=%u\n", iob, len, offset);
	DEBUGASSERT(iob && src);

	/* The offset must applied to data that is already in the I/O buffer chain */

	if (offset > iob->io_pktlen) {
		ioberr("ERROR: offset is past the end of data: %u > %u\n", offset, iob->io_pktlen);
		return -ESPIPE;
	}

	/* Skip to the I/O buffer containing the data offset */

	while (offset > iob->io_len) {
		offset -= iob->io_len;
		iob = iob->io_flink;
	}

	/* Then loop until all of the I/O data is copied from the user buffer */

	while (len > 0) {
		next = iob->io_flink;

		/* Get the destination I/O buffer address and the amount of data
		 * available from that address.
		 */

		dest = &iob->io_data[iob->io_offset + offset];
		avail = iob->io_len - offset;

		iobinfo("iob=%p avail=%u len=%u next=%p\n", iob, avail, len, next);

		/* Will the rest of the copy fit into this buffer, overwriting
		 * existing data.
		 */

		if (len > avail) {
			/* No.. Is this the last buffer in the chain? */

			if (next) {
				/* No.. clip to size that will overwrite.  We cannot
				 * extend the length of an I/O block in mid-chain.
				 */

				ncopy = avail;
			} else {
				unsigned int maxlen;
				unsigned int newlen;

				/* Yes.. We can extend this buffer to the up to the very end. */

				maxlen = CONFIG_IOB_BUFSIZE - iob->io_offset;

				/* This is the new buffer length that we need.  Of course,
				 * clipped to the maximum possible size in this buffer.
				 */

				newlen = len + offset;
				if (newlen > maxlen) {
					newlen = maxlen;
				}

				/* Set the new length and increment the packet length */

				head->io_pktlen += (newlen - iob->io_len);
				iob->io_len = newlen;

				/* Set the new number of bytes to copy */

				ncopy = newlen - offset;
			}
		} else {
			/* Yes.. Copy all of the remaining bytes */

			ncopy = len;
		}

		/* Copy from the user buffer to the I/O buffer.  */

		memcpy(dest, src, ncopy);
		iobinfo("iob=%p Copy %u bytes new len=%u\n", iob, ncopy, iob->io_len);

		/* Adjust the total length of the copy and the destination address in
		 * the user buffer.
		 */

		len -= ncopy;
		src += ncopy;

		/* Skip to the next I/O buffer in the chain.  First, check if we
		 * are at the end of the buffer chain.
		 */

		if (len > 0 && !next) {
			/* Yes.. allocate a new buffer.
			 *
			 * Copy as many bytes as possible.  If we have successfully copied
			 * any already don't block, otherwise block if we're allowed.
			 */

			if (!can_block || len < total) {
				next = iob_tryalloc(throttled);
			} else {
				next = iob_alloc(throttled);
			}

			if (next == NULL) {
				ioberr("ERROR: Failed to allocate I/O buffer\n");
				return len;
			}

			/* Add the new, empty I/O buffer to the end of the buffer chain. */

			iob->io_flink = next;
			iobinfo("iob=%p added to the chain\n", iob);
		}

		iob = next;
		offset = 0;
	}

	return 0;
}

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: iob_copyin
 *
 * Description:
 *  Copy data 'len' bytes from a user buffer into the I/O buffer chain,
 *  starting at 'offset', extending the chain as necessary.
 *
 ****************************************************************************/

int iob_copyin(FAR struct iob_s *iob, FAR const uint8_t *src, unsigned int len, unsigned int offset, bool throttled)
{
	return len - iob_copyin_internal(iob, src, len, offset, throttled, true);
}

/****************************************************************************
 * Name: iob_trycopyin
 *
 * Description:
 *  Copy data 'len' bytes from a user buffer into the I/O buffer chain,
 *  starting at 'offset', extending the chain as necessary BUT without
 *  waiting if buffers are not available.
 *
 ****************************************************************************/

int iob_trycopyin(FAR struct iob_s *iob, FAR const uint8_t *src, unsigned int len, unsigned int offset, bool throttled)
{
	if (iob_copyin_internal(iob, src, len, offset, throttled, false) == 0) {
		return len;
	} else {
		return -ENOMEM;
	}
}
